I found this amazing summary from GMAT Genius's review of the book on amazon:

OVERVIEW of OFFICIAL GUIDE 2018

The Official Guides for GMAT Review contain retired real GMAT questions, and are an essential component of your GMAT preparations. The GMAC places questions in order of increasing difficulty, based on its assessment of difficulty. The Quantitative Official Guide has no overlap with questions in the main Official Guide.

The 2018 edition of this book contains 45 new questions out of the 300 total questions, representing 15% new content. These are new questions that we have not encountered before; they are not questions recycled from older GMAC resources.

The Problem Solving section contains 26 new questions, with difficulty of Easy / Medium / Hard as follows: 15 / 5 / 6. This is in lieu of 26 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 11 / 14 / 1. Unlike in prior years, the GMAC has not reclassified the difficulty of any question.

In the Data Sufficiency section, questions are not fully presented in order of progressive difficulty, contrary to what the back cover of the book claims. Based on difficulty levels provided in the online version, Medium and Hard difficulty questions are interspersed. The following lists the question numbers for each difficulty level:
Easy - 177-203
Medium - 204-235, 239
Hard - 236-238, 240-300

The Data Sufficiency section contains 19 new questions, with difficulty of Easy / Medium / Hard as follows: 2 / 6 / 11. This is in lieu of 19 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 1 / 4 / 14. The GMAC has not reclassified the difficulty of any question.

Thanks for this, but I am looking for the same as you find but for the OG "QUANTITATIVE" Review book. The one that comes with only math questions... Do you have for this?

barksdale wrote:

I found this amazing summary from GMAT Genius's review of the book on amazon:

OVERVIEW of OFFICIAL GUIDE 2018

The Official Guides for GMAT Review contain retired real GMAT questions, and are an essential component of your GMAT preparations. The GMAC places questions in order of increasing difficulty, based on its assessment of difficulty. The Quantitative Official Guide has no overlap with questions in the main Official Guide.

The 2018 edition of this book contains 45 new questions out of the 300 total questions, representing 15% new content. These are new questions that we have not encountered before; they are not questions recycled from older GMAC resources.

The Problem Solving section contains 26 new questions, with difficulty of Easy / Medium / Hard as follows: 15 / 5 / 6. This is in lieu of 26 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 11 / 14 / 1. Unlike in prior years, the GMAC has not reclassified the difficulty of any question.

In the Data Sufficiency section, questions are not fully presented in order of progressive difficulty, contrary to what the back cover of the book claims. Based on difficulty levels provided in the online version, Medium and Hard difficulty questions are interspersed. The following lists the question numbers for each difficulty level:
Easy - 177-203
Medium - 204-235, 239
Hard - 236-238, 240-300

The Data Sufficiency section contains 19 new questions, with difficulty of Easy / Medium / Hard as follows: 2 / 6 / 11. This is in lieu of 19 questions from the 2017 edition that have been removed, with difficulty of Easy / Medium / Hard as follows: 1 / 4 / 14. The GMAC has not reclassified the difficulty of any question.